Programs across the country are trying to make it easier for new farmers to get started and put down roots. Here’s why: There’s only one farmer under 35 for every six over 65. By 2030, one-quarter of America’s current farmers will retire.

Against a backdrop of lush green mountains and swaying papaya trees, La‘amea Lunn readies his crop of carrots, kale, and eggplants for the weekly farmers market. He carefully tends his one-third acre on Oahu, Hawai‘i, preparing produce for a market stall he shares with friends—young farmers like himself, a few of whom he met when they worked neighboring plots on this land owned by the University of Hawai‘i.

At 32, Lunn has an office job with a career in restaurant kitchens behind him. He hopes to own a farm of his own, to be […]